As information technology has rapidly progressed, computer network centers such as server farms and server clusters have become increasingly important to our society. The server farms provide efficient data processing, storage, and distribution capability that supports a worldwide information infrastructure, which has come to dominate how we live and how we conduct our day to day business. A server farm is a group or cluster of computers acting as servers and housed together in a single location.
Typically, at a site where numerous computers are connected to a network, the computers are stacked in racks and arranged in repeating rows or cells. Access to the computers may be needed for servicing, upgrading hardware, loading software, attaching cables, switching power on and off, and so forth. The elimination of as much access space as is feasible can increase the density of computer systems that may be provided for a given square footage of area at a site.
A standard rack that is widely used measures roughly 19 inches wide, 30 inches deep and 74 inches high. These racks may be arranged in rows of, for example, roughly 10-30 units, with access doors on each side of the racks. Access aisles are provided on both sides of the rows so that an operator may approach the access doors on each side. Many of the racks are filled with cumbersome computers mounted on sliders which are attached through mounting holes provided in the front and back of the rack.
In conventional rack-based computer systems, a plurality of computers are supported in a single stack in a rack. The rack may include a rack assembly having a front door and a back door. Each of the computers typically includes a computer chassis having a main board and other components, such as one or more power supplies, hard drives, processors, expansion cards, contained within the chassis. The front door of the rack assembly provides access to the front sides of the computers and the back door provides access to the back sides, where the I/O ports for the computers are typically provided. Each computer may also include one or more fans that draw ambient air into vents provided on one side of the computer, through the computer chassis, and out of vents provided on the opposite side of the computer. The ambient air passing through the computers is used to cool the various components contained within the computer chassis.
In order to optimize the cooling of the rack-mounted computer systems, many data centers utilize a hot aisle/cold aisle layout in which the computers in adjacent rows alternate directions. Thus, the front sides of the computers in a first row face the front sides of the computers in an adjacent row, and the back sides of the computers in the first row face the back sides of the computers in an adjacent row. As a result, cold air is segregated in front of equipment cabinets and hot exhaust air is expelled behind equipment cabinets. The HVAC (heating, ventilation and air-conditioning) system is configured to deliver cold air to the cold aisles (typically through perforated floor tiles) and to vent heated air from the hot aisles (typically through vents in the ceiling). This layout avoids the direct transfer of hot exhaust air from one system into the intake air of another system.
As the number of computers in a server farm is increased, two competing factors come into play: consumption of floor space and heat management. As one increases the density of computers, problems associated with heat dissipation rise dramatically. One of the major causes of electronic component failure is overheating. High performance electronics such as CPUs generate substantial amounts of heat. Hard drives and power supplies generate substantial amounts of heat as well, thereby placing further demands on effective heat dissipation. In order for computers to continue to operate properly, appropriate heat dissipation pathways should be provided. Because each computer contains thousands of heat producing electronic parts, as the density of the computers is increased, one must also address the difficult issues of providing proper cooling mechanisms to remove heat from the individual computer nodes and the clusters as a whole. Therefore, it is desirable to provide an improved cooling system for rack-based computer systems.